Static and dynamic turbidity sensing in a washing appliance

ABSTRACT

A method is provided for measuring detergent and soil in wash water of a dishwashing or clothes washing appliance. A turbidity sensor is used to sense or measure the soil in the water in a static state, and to sense or measure the detergent in the water during a dynamic state. The turbidity sensor generates a corresponding output signal which is sent to a microprocessor to automatically adjust machine cycles to increase operational efficiencies.

BACKGROUND OF THE INVENTION

[0001] The use of turbidity sensors in dishwashing machines and clothes washing machines is well known. The sensors typically measure the amount of food, soil or dirt in the wash water, with the water being recirculated until a predetermined level of soil has accumulated, after which the dirty water is drained.

[0002] “Smart” dishwashers have been developed which automatically determine particular parameters to adjust the operation of the dishwasher. For example, in Applicant's U.S. Pat. No. 5,797,409, the presence of a rinse aid is detected by measuring turbidity of the water after the rinse aid should have been dispensed and comparing the measured turbidity to a known turbidity for clear water using a turbidity sensor. If no rinse aid is detected, additional time is added to the drying cycle.

[0003] Similarly, U.S. Pat. No. 5,331,177 discloses a “smart” dishwasher which utilizes turbidity caused only by detergent, so as to automatically abort the cycle and save energy.

[0004] Dish and clothes washing appliances have two distinct operational states. First, the washer has a static state in which no components are in motion that cause disturbance within the wash water. Secondly, the washer has a dynamic state wherein one or more components are disturbing the wash water. A turbidity sensor is typically extremely sensitive to detergent in the wash water when the washer is in a dynamic state, and far less sensitive to detergent in the wash water when the washing machine is in a static state.

[0005] Accordingly, a primary objective of the present invention is the use of a turbidity sensor in a washing appliance to sense soil or dirt within the wash water when the washer is in a static state, and to sense detergent in the wash water when the washer is in a dynamic state.

[0006] Another objective of the present invention is the provision of measuring detergent and soil in wash water of a washing appliance so as to allow adjustments in the operational cycles of the appliance.

[0007] A further objective of the present invention is the provision of a method for determining the presence of detergent and soil in wash water of a clothes washing machine or dishwasher, with the appliance automatically making cyclical adjustments in response to the presence or absence of detergent and/or soil in the water.

[0008] Another objective of the present invention is the provision of a method for verifying that detergent has been properly dispensed in a dishwashing machine or clothes washing machine.

[0009] Another objective of the present invention is the provision of a method for minimizing or eliminating detergent-induced spotting on items in a dishwasher.

[0010] Another objective of the present invention is the provision of an improved smart washing appliance which automatically responds to wash water turbidity in the static and dynamic states.

[0011] These and other objectives will become apparent from the following description of the invention.

SUMMARY OF THE INVENTION

[0012] A method is provided for measuring detergent and soil in wash water of a dishwashing machine and clothes washing machine, wherein the soil is sensed or measured during a static state and the detergent is sensed or measured during a dynamic state using a turbidity sensor. The detergent is sensed both before and after a detergent dispensing operation to determine that detergent is properly dispensed. Lack of detergent identifies when a bulk detergent dispenser is empty or the dispenser is malfunctioning. Cycle decisions, such as the length of the final rinse, can be made based upon the detergent level in the wash water. Cycle decisions can also be made based upon the sensing of the soil in the wash water, such as the need for a longer wash cycle.

DETAILED DESCRIPTION OF THE INVENTION

[0013] Dishwashers and clothes washers have two distinct operational states that exist during the operation of the appliance. The static state is one in which no components, such as pumps and heaters, are active, such that there is no disturbance within the wash water. The dynamic state is one in which one or more components are active, and by their nature, cause a disturbance in the wash water.

[0014] An analog turbidity sensor can be designed for two characteristics to occur. First, the sensor is extremely sensitive to detergent in the wash water when the appliance is in a dynamic state. Second, the sensor is far less sensitive to detergent in the wash water when the appliance is in the static state. These characteristics allow the turbidity sensor to be used to sense soil within the wash water during the static state, and to sense detergent in the wash water when the appliance is in the dynamic state. Accordingly, turbidity measurements by the turbidity sensor can be used to make automatic cycle decisions based upon either the soil or the detergent content of the wash water.

[0015] For example, during the prewash cycle of the machine, the soil content of the water can be sensed and measured by the turbidity sensor, with the output being used by a microprocessor in the machine to automatically adjust the wash cycle to ensure adequate washing. As another example, the same turbidity sensor can be used to sense and measure the detergent content of the wash water in the final rinse cycle of the machine, with the microprocessor automatically adjusting the cycle to reduce or eliminate detergent. In a dishwasher, such sensing and cycle adjustment will minimize detergent-induced spotting on the dishes, glasses and silverware. If the sensed level of detergent is above a preset threshold level, an extra rinse cycle can be automatically added so as to eliminate the detergent-induced spotting.

[0016] The method of measuring or determining detergent in the wash water also allows verification that detergent has been properly dispensed into the wash water of the clothes washing machine or dishwashing machine. More particularly, the turbidity of the water is measured both before and after the detergent dispensing operation to verify that the appropriate change in the turbidity sensor output has taken place. In a machine with a bulk detergent dispenser, this process can be used to indicate that the dispenser has run out of detergent or is malfunctioning.

[0017] As an alternative, the turbidity sensor can also be used during the dynamic status to determine the presence of both soil and detergent in the wash water and generate an output signal to which the microprocessor can react to adjust the operational cycles accordingly.

[0018] Thus, the method of determining the presence of detergent and soil in the wash water, according to the present invention, allows various decisions to be made regarding the various washing cycles, so that alterations can be automatically made to increase efficiency based upon signals from the turbidity sensor in both the static and dynamic states.

[0019] The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. From the foregoing, it can be seen that the present invention accomplishes at least all of its stated objectives. 

What is claimed is:
 1. A method of measuring detergent and soil in wash water of a washing appliance, comprising: sensing soil in the water when the appliance is in a static state; and sensing detergent in the water when the appliance is in a dynamic state.
 2. The method of claim 1 wherein the sensing of soil and detergent is accomplished with a turbidity sensor.
 3. The method of claim 1 wherein the detergent is sensed before a detergent dispensing operation.
 4. The method of claim 1 wherein the detergent is sensed after a detergent dispensing operation.
 5. The method of claim 1 wherein the detergent is sensed both before and after a detergent dispensing operation.
 6. The method of claim 1 further comprising making cycle decisions based on the sensing of the soil.
 7. The method of claim 6 wherein the cycle decision relates to a wash cycle.
 8. The method of claim 1 further comprising making cycle decisions based on the sensing of the detergent.
 9. The method of claim 8 wherein the cycle decision relates to a final rinse.
 10. The method of claim 1 wherein the sensing of detergent verifies that detergent has been dispensed into the water.
 11. The method of claim 1 wherein the sensing of detergent identifies when a bulk detergent dispenser is empty.
 12. The method of claim 1 wherein the sensing of detergent identifies malfunctioning of a detergent dispenser.
 13. The method of claim 1 wherein the sensing of detergent allows for cycle adjustment to minimize detergent-induced spotting on items in the washing appliance.
 14. A method of determining the presence of detergent and soil in wash water of a washing appliance, comprising: measuring the water turbidity during a static state, with the turbidity correlating to soil in the water; and measuring water turbidity during a dynamic state, with the turbidity correlating to detergent in the water.
 15. The method of claim 14 wherein the turbidity is measured using a turbidity sensor.
 16. The method of claim 14 wherein the turbidity in the dynamic state is measured before a detergent dispensing operation.
 17. The method of claim 14 wherein the turbidity in the dynamic state is measured after a detergent dispensing operation.
 18. The method of claim 14 wherein the turbidity in the dynamic state is measured before and after a detergent dispensing operation.
 19. The method of claim 14 further comprising making cycle decisions based on the turbidity measurements.
 20. The method of claim 19 wherein the cycle decision relates to a final rinse.
 21. The method of claim 19 wherein the cycle decision relates to a wash cycle.
 22. The method of claim 14 wherein measuring turbidity in the dynamic state verifies that detergent has been dispensed into the water.
 23. The method of claim 14 wherein measuring turbidity in the dynamic state identifies when a bulk detergent dispenser is empty.
 24. The method of claim 14 wherein measuring turbidity in the dynamic state identifies functioning of a detergent dispenser.
 25. The method of claim 14 wherein measuring turbidity in the dynamic state allows for cycle adjustment to minimize detergent-induced spotting on items in the appliance. 